Sewage lift station structure



United States Patent [72] lnventor John W. Parks Overland Park, Kansas [21] Appl. No, 759,947 [22] Filed Sept. 16, 1968 [45] Patented Aug. 25, 1970 [73] Assignee Union Tank Car Company Chicago, Illinois a corporation of Delaware [54] SEWAGE LIFT STATION STRUCTURE 7 Claims, 2 Drawing Figs.

[52] US. Cl 137/363, 220/69 [51] Int. Cl F1615/00 [50] Field ofSearch 220/66, 69; 137/356 373 [56] References Cited UNITED STATES PATENTS 1,141,846 6/1915 Spremulli et a1 220/69 I I w Primary Examiner Henry T. Klinksiek Art0rne vHume, Clement, Hume, Lee and Charles M.

Kaplan ABSTRACT: A sewage lift station construction wherein a vertically disposed, cylindrical housing for the lift equipment has a domed bottom which provides its own support in compressive stress under external load. The lift equipment is supported within the housing on four column members pinned in pivotal relationship at their upper ends to the equipment and welded in suitable angular relationship at their lower ends to the inner surface of the domed floor, A plurality of yieldable support legs for the housing below the floor are designed to fail individually under load prior to failure of the housing itself.

Patented Aug. 25, 1970 3,525,353

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J0 2/ QM! SEWAGE LIFT STATION STRUCTURE BACKGROUND OF THE INVENTION This invention relates in general to sewage lift stations. It deals more particularly with the construction and support of sewage lift stations and their contents.

It is conventional to employ a vertically disposed cylindrical structure as the housing for a sewage lift station; a pump station, for example. Such a housing usually includes a flat floor reinforced by structural members on the outside. This construction has, in the past, been considered the most practical form of pump station, the top of the station normally being covered by a roof which might be flat or, under some circumstances, domed.

There are several significant disadvantages to the flat form construction in sewage lift stations, however. For example, the welds between the floor and the reinforcing beams develop pits and other surface imperfections which make thorough coating with paint difficult. As a result, corrosion starts rather easily. In this light, the beams have relatively sharp corners and edges which cannot be well coated and also contribute to the corrosion problem. In this same vein, the surfaces of the floor and beams which are in contact with each other cannot be coated, and where any imperfections in the weld are found, moisture enters between the surfaces and causes corrosion.

In addition to the foregoing corrosion problems, with a flat floor and beamed support structure, relatively large deflections occur due to external pressure from back fill and ground water in which the lift station is disposed. These deflections cause the elevation of a pump in such a station, for example, relative to the remainder of the internal structure of the station, causing stress in pipe connections and the like.

In addition to the foregoing, it is not uncommon for welding between the floor and the supporting beams to cause warpage of the floor whereby depressions are naturally formed therein. These depressions often collect and hold moisture even though the entire cylindrical structure is tipped to promote drainage. Corrosion again results.

SUMMARY OF THE INVENTION The present invention is embodied in a domed floor construction on a cylindrical lift station such as a pump station or the like, as well as in the support structure for the lift station. Accordingly, it is an object to provide an improved structure for a sewage lift station such as a pump station or the like. It is another object to provide a new and improved floor construction for a sewage lift station. It is still another object to provide a floor construction which is effective to substantially eliminate corrosion problems on the exterior of the floor. It is a further object to provide a floor structure of the aforedescribed character which has a greatly improved structural strength-to-weight ratio.

It is still a further object to provide a floor structure to a sewage lift station or the like wherein interior floor drainage problems are eliminated. Yet a further object is to provide a new and improved equipment mounting arrangement for equipment disposed within the lift station housing.

Finally, it is also an object of the present invention to provide an improved support structure for the housing of a sewage lift station. Sewage lift stations of the type in question normally have relatively thin-walled housings which sometimes fail under unusual handling loads. The support structure of the present invention is adapted to fail under the shock or unusual handling loads, rather than the housing, while supporting the housing in a conventional manner under normal conditions.

The foregoing and other objects are realized in accord with the present invention by providing a cylindrical sewage lift station, such as a pumping station, for example, with a domed floor. The domed floor has no external beam supports. Accordingly, the corrosion problems normally encountered when support beams are welded to a flat floor, for example, are virtually eliminated. All of the external surface of the floor can be completely painted. The domed floor readily drains to a central pump without tipping, thus eliminating the problem of internal corrosion on the floor.

There is virtually no deflection of the floor, since it carries external pressure in compression. Internally mounted pumps, two for example, and their piping are supported by simple, single column supports at four points. These supports are short, stiff columns which are pin-ended and are attached to the pumps and piping by a single bolt. This permits them to be rotated any required amount for engagement with the domed floor with the pump in proper elevation and attitude. The pins are then welded to the floor. They thus accommodate dimensional variations in various components of the structure.

The support structure for the housing embodying features of the invention is a multiplicity of members designed so that under normal load they will support the structure, but at a predetermined load level above the normal load they will fail either in buckling or in bending. This predetermined load level is below the housing load limit. Sufficient supports are furnished so that failure of one or two leaves a balance capa' ble of supporting the structure. By varying quantity, length, cross-sectional area, and moment of inertia of the supports, and by selecting support materials with desired physical properties, any combination of support strength and failure point can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS The invention, together with its construction and method of operation, taken with other objects and advantages thereof, is illustrated more or less diagrammatically in the drawing, in which:

FIG. 1 is a top plan view, with parts removed, of the improved structure of a sewage lift station embodying features of the present invention; and

FIG. 2 is a sectional view of the structure taken along line 2- -2 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, and particularly to FIGS. 1 and 2, a portion of the sewage pump station embodying features of the present invention is illustrated generally at 10. The pump station 10 comprises a pump housing 11, constructed according to the invention, containing a dual-pump station 12, supported inside the housing on a mounting assembly 13 also embodying features of the invention.

The housing 11, with its enclosed dual-pump system 12, is mounted on a yieldable support structure 15 embodying other features of the invention. The yieldable support structure 15 readily supports the normal load of the housing 11 and pump system 12, but, if the unit is mishandled; dropped, for example, in installation, at a predetermined load level below the failure limit of the housing 11 the support structure 15 buckles locally. The structure is constructed so sufficient of it remains to support the unit. Nevertheless, buckling of the localized portions of the support structure 15 prevents damage to the housing 11 itself and, accordingly, its contained pump system 12.

The housing 11 itself includes a right, circular cylindrical side wall 20 fabricated of sheet steel or the like. Closing the upper end of the housing 11 is a roof (not shown) also fabricated of sheet steel. A circular access manhole in the roof affords access to the housing 11.

According to the invention, the floor 30 of the housing 11 is fabricated in the shape of a dome. As such, it is segmentally spherical throughout the circular section 31 between its cylindrical outer rim 32 and an annular aperture 33 formed in its center. The annular outer rim 32 of the domed floor 30 is welded to the correspondingly annular lower edge of the side wall 20.

Extending downwardly from the aperture 33 in the center of the floor 30 is a generally cylindrical sump or well 35. The well 35 also has a domed floor 36 in it, the radius of curvature of the domed floor 36 in the well 35 corresponding substantially to the radius of curvature of the section 31 of the floor 30 in the housing 11.

The dual pump system 12 is, as has been previously pointed out, mounted within the housing 11 on a mounting assembly 13 embodying features of the present invention. The pump system 12 comprises, in the present illustration, an identical pair of vertical shaft, centrifugal pump units 40. Each of the pump units 40 is substantially identical in construction and operation to that illustrated and described generally in the copending application of Frank G. Weis, Ser. No. 761,023, filed Sept. 20, l968, and entitled Pump Priming System, and assigned to the same assignee as the present invention.

Each pump unit 40 includes a conventional pump inlet elbow 41. Each pump inlet elbow 41 is joined, at mating flanges 42, to inlet piping 43, which extends horizontally through the housing 11 at the juncture of the domed floor 30 and the side wall through a suitable fitting 44.

The outlet nozzle 50 of each pump unit 40 extends tangentially from the volute casing 52 of the units. Each nozzle 50 is joined, at a mating flange 51, to a corresponding outlet pipe section 53. The pipe sections 53 connect the nozzles 50 to a common Y-pipe 55 at mating flanges 60. The Y-pipe 55 extends through the wall 20 at the fitting 61.

It will thus be seen that the pump units 40 of the dual pump system 12 are rigidly interconnected by the nozzle and pipe complex 50, 52, 55 and their intermediate joints 51 and 60. The dual pump system 12 is, in turn, supported from the domed floor of the housing 11 through the mounting assembly 13 embodying features of the invention.

The mounting assembly 13 for the dual pump system 12 comprises four short, stiff columns 65, 65, 66 and 66 fabricated of angle members. The columns 65 are identical to each other and each is pinned in pivotal relationship to joint flanges 42 between a corresponding pipe section 43 and inlet elbow 41. In turn, the columns 66 are each pinned in pivotal relationship to the joint flanges 51 between corresponding outlet nozzles 50 and pipe sections 53.

In the illustration shown, the columns 65, 66 are all shown in precisely vertical relationship with their lower ends welded in a conventional manner to the inner surface 70 of the curved section 31 in the domed floor 30. This is an idealized relationship, however. In practice, according to the invention, the dual pump unit 12 is lowered into the housing 11 with the roof removed and the columns 65, 66 pinned to corresponding flanges. The columns 65, 66 are then individually pivoted on their connections with corresponding flanges into engagement with the floor 30 in such a manner that the dual pump system 12 is in perfectly horizontal relationship. In this relationship the free lower ends of the columns 65, 66 are welded to the floor 30.

The domed floor 30 requires no external support since it carries all, or substantially all, external pressure in compression. Accordingly, the corrosion problems normally created when support beams are welded to a flat floor, for example, are virtually eliminated, as has been pointed out. Furthermore, the domed floor 30 drains to the central sump without tipping.

The domed floor 30 suffers virtually no deflection under external pressure. Accordingly, the dual pump system 12 remains in its original position in the housing 11, and the fittings 44, 61 carry the inlet pipes and the outlet pipes through the housing 11 undisturbed, thus minimizing stress in the housing at the pump system 12 at these fittings.

The columns supports 65,66 are an ultimately simple mode of support for the dual pump system 12. They can be rotated into any angular relationship wherein their free ends come into contact with the floor 30 of the housing 11 with the dual pump system 12 in perfectly horizontal relationship. Thus, precise horizontal mounting of the dual pump system 12 in the field is readily achieved.

The yieldable support structure 15 readily supports the normal load of the housing and the pump system 12, as has been pointed out. lt includes, in the present illustration, six inch steel bars 75 bent at right angles in the manner illustrated 11'] as at 77.

The multiplicity of angle bars 75 are designed so that under normal load they will support the housing 11 and its contained pump units 12, but at a predetermined load level above this normal load they will fail either in buckling or bending. The predetermined load level is below the load limit of the housing strucutre itself. If the unit 10 is inadvertently dropped a short distance, for example, several of the angle bars 75 might readily fail, but the housing 11 does not. Sufficient of the bars 75 are provided, however, so that failure of one or two leaves a balance capable of supporting the structure.

While the embodiment described herein is at present considered to be preferred, it is understood that various modifications and improvements may be made therein, and it is in tended to cover in the appended claims all such modifications and improvements as fall within the true spirit and scope of the invention.

1 claim:

1. A sewage lift station structure, comprising:

a. a housing enclosing sewage lift equipment;

b. said housing having a vertically disposed, generally cylindrical side wall;

c. a floor on said housing;

said floor having a downwardly domed configuration;

e. said housing being fabricated of metal plate and having a predetermined bending stress limit;

f. and yieldable support means under said floor supporting said housing, the bending stress limit of said yieldable support means being less than said predetermined stress limit.

2. The sewage lift station structure of claim 1 further characterized by and including:

a. column means supporting said sewage lift equipment within said housing;

b. said column means being welded to said domed floor.

3. The sewage lift station structure of claim 2 further characterized in that:

a. said column means comprises a plurality of vertical columns;

b. the upper end of each of said columns being pinned in pivotal relationship to said sewage lift equipment.

4. The sewage lift station structure of claim 1 further characterized in that:

a. said downwardly domed floor includes an annular section having a segmentally substantially spherical configuration.

5. The sewage lift station structure of claim 1 further characterized in that:

a. said vertically disposed, generally cylindrical side wall defines a right circular cylinder.

6. The sewage lift station structure of claim 1 further characterized in that:

a. said yieldable support means comprises a plurality of separately yieldable members annularly spaced under said floor.

7. The sewage lift station structure of claim 6 further characterized in that:

a. said separately yieldable members each comprise an angle bar having an inner end welded to said downwardly domed floor adjacent its center and an outer end welded to said downwardly domed floor adjacent its outer periphery. 

